GMC Sierra 1500 HD intermittent fan runs when vehicle is off, suspected cause of battery drain on GMC Sierra 1500 HD

Some GMC Sierra 1500 HD owners report experiencing intermittent fan operation, particularly when the vehicle is off, which can lead to battery drain. This issue may stem from a faulty blower motor, characterized by louder sounds and unusual whirring noises when the fan operates at full speed. Additionally, some owners find that the radiator fans run constantly after shutdown, potentially indicating problems with the cooling system, such as a faulty sensor or thermostat. An improperly functioning thermostat that opens too soon can also cause the fans to operate unnecessarily. Furthermore, some owners have had success in resolving intermittent operation issues by cleaning the rheostat through rapid cycling of the control from minimum to maximum. To mitigate these problems and prevent battery drain, it is recommended that owners inspect the blower motor, radiator fans, sensors, thermostat, and rheostat for any underlying issues.